Runny nose could be caused by general nasal irritants or an infection. I’ve also heard once or twice that dental problems can cause some nose issues (kind of like in humans, when you have a tooth extracted or dental procedure, you may get a really runny nose). My only experience from Wick is a runny nose due to an upper respiratory infection (URI), but that came about with sneezing, so it may or may not be the same case to you. I’m more leaning towards allergies since it seems pretty tame. On the flip side, it could be just very slow developing, so sneezing isn’t a reaction as of yet.
Hay dust can do it, so if the hay from the portion of your hay bag that you’re currently on is dustier, it could cause some runny nose. Dust from carpeting and the air could as well, so if it’s been a while since you’ve vacuumed, dust, etc., there may be more in the air to irritate the nose. My vet did tell me something interesting in terms of hay brands. Wick was originally on Kaytee timothy hay, but with his URI, I wanted to try something less-dusty to get the sneezing a bit more under control. My vet pointed out that it may not just be dust hay, but different companies will grow their hay in different environments, so it’s possible that where Kaytee cultivates its hay is filled with something that really irritates Wick. I changed to Oxbow timothy, and voila, sneezing was much lesser. Wick still needed treatment for the actual URI and the sneezing caused directly by it, but switching hay brands helped.
The answers provided in this discussion are for general guideline purposes only. The information is not intended to diagnose or treat your pet. Seek the advice of your veterinarian or a qualified behaviorist.